JP2724949B2 - Spread spectrum communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum system, and more particularly to a spread spectrum communication system using direct spreading.

[0002]

2. Description of the Related Art In conventional data communication, communication using a narrow band modulation method (AM, FM, BPSK, etc.) is generally used. These can realize demodulation in a receiver with a relatively small circuit, but can be used indoors (offices, factories, etc.).
Is disadvantageous in that it is susceptible to multipath and narrowband colored noise.

On the other hand, in the spread spectrum communication system, the spectrum of data is spread by a spreading code,
Since transmission is performed in a wide band, there is an advantage that these disadvantages can be eliminated.

Among such spread spectrum communication systems, the direct spread system has already been partially put into practical use. The direct spreading despreading includes active correlation methods such as sliding correlation and passive types such as matched filters and correlators. As an active correlation method, it is necessary to maintain synchronization using a tracking loop such as a DLL loop even after synchronization is acquired.

However, this method has a drawback that it takes a long time to acquire the synchronization because the chip of the code is shifted a little at a time in order to perform the synchronization acquisition and a timing matching the code is found. It is good to have a fixed propagation path line, but in a line such as a room where the propagation path changes frequently, once synchronization is lost, it takes time to synchronize again, so that it cannot be used.

A passive despreading method used for such a line will be described with reference to FIG. In FIG. 13, the input IF signal is frequency-converted by a multiplying circuit 50 into an I component and a Q component of a local signal to become a baseband I component 51 and a Q component 52. These two inputs are input to an I-channel correlator 53 and a Q-channel correlator 54, and are correlated with each other.
The correlation output 55 is input to a data demodulation circuit 56, and data 57 is output. On the other hand, using the respective correlation outputs 55 and 58 to the I and Q channels, the loop control circuit 59 controls the control voltage 60 for the local oscillator 61.
Is determined, and the local oscillator 61 is controlled such that the phases of the local oscillator 61 and the IF carrier are synchronized.

FIG. 14 is a diagram showing the output of a correlator having a form similar to a Costas loop. A correlation output is generated when the spread codes exactly match, and becomes almost zero at other positions. For example, when the spread code is 127 chips, the correlation output is output only for 1/127 of the time, and the loop control circuit 59 loops using the phase error that can be read from this 1/127 time. Therefore, the general analog Costas (PL
L) A circuit slightly different from the loop is required. Also,
The data demodulation circuit 56 determines whether the data is "1" or "0" from such a pulse signal, and reproduces the clock to obtain the data.

[0008]

As described above, in a passive circuit, demodulation can be performed in the same manner as general narrow-band digital modulation, but there are also the following problems.

Due to having a carrier regeneration circuit,
It takes a long time for the carriers to synchronize and is much faster than the active type. However, if the path is frequently changed and the carrier synchronization is lost, data cannot be demodulated for the time required for the synchronization.

FIG. 15 shows a correlator output when there are many multipaths. In this way, several correlator outputs are output according to the multipath propagation time difference. In such a case, when the output is used to judge the data, or when detecting with the total power, a method of opening a window on the time axis and integrating during that time is adopted, but how long and at what time the window is opened Is difficult because the optimum value changes for each path.

The output data has two stable points, 0 and π, depending on the phase of the carrier. Since the data is inverted, it is devised to perform differential encoding or to determine the data based on a preamble signal of the data. Is required.

In order for a user to perform multi-access, a technique of dividing the spread code according to the difference is adopted. However, for example, in the case of an m series of 127 chips, there are only 18 types of codes, and no more users can access.

Therefore, a main object of the present invention is to provide a spread spectrum communication system which does not require carrier regeneration.

[0014]

The invention according to claim 1 is
A signal obtained by modulating a carrier with a spreading code and data and two waves modulated only by a spreading code are generated, one of which is delayed by at least one chip of the spreading code, multiplexed and transmitted, and the receiving side converts the received signal into two waves. Then, only one of the waves is delayed, and the two waves are divided into I and Q components and frequency-converted into a pseudo baseband component. Thereafter, the four signals are input to the correlator, the respective correlation outputs are obtained, the I components or the Q components are multiplied, and the data is demodulated by adding the two multiplication outputs.

At this time, various processing is performed on the subsequent data output using the earliest correlation output not used for data output. Further, the number of users is increased by utilizing the multiplicity of both the delay amount and the spreading code, and the intra-cell or inter-cell distinction is performed in a cellular network system. Also, the receiving side may delay the signal after converting it into a pseudo baseband component divided into an I component and a Q component.

Further, the signals to be multiplexed are changed by changing the amount of delay.
It may be more than a wave. By changing the number of multiplexes, data can be varied.

[0017]

The spread spectrum system according to the present invention delays one of two signals, that is, a signal modulated only by a spread code and a signal modulated by a spread code and data, and multiplexes and transmits them. The data is demodulated by dividing into two, and leaving one as it is, and delaying the other as I and Q baseband components and inputting the result to the correlator, multiplying and adding the correlator output, and demodulating the data. You can get the output.

Further, since a correlation output is obtained before the data to be output, the correlation output can be analyzed and optimal integration, filtering and time window control can be performed, and the effect of PDI can be maximized.

Further, by combining the spreading code and the delay amount, it is possible to increase the number of user layers capable of multi-access,
Multiple access management can be performed separately for the spreading code and the delay amount.

Further, by using a plurality of delay amounts in one terminal station, data can be multiplexed, and a higher-speed data transmission and a variable data transmission speed system can be realized.

[0021]

1 and 2 show a first embodiment of the present invention. In particular, FIG. 1 shows a transmitter, and FIG. 2 shows a receiver.

In the transmitter shown in FIG. 1, a signal generated by data
The PN code generated by the N generator 132 is multiplied. After that, the output of the multiplier 131 modulates the local signal L1 by the modulator 133 to become a BPSK modulated wave, and is thereafter delayed by the delay element 115 for an arbitrary time τ. on the other hand,
In modulator 112, BPSK modulated only by PN code
Generate a modulated wave. The two BPSK modulated waves are multiplexed by a multiplexer 116, frequency-converted by a frequency converter 117, power-amplified by a power amplifier 118, and transmitted from an antenna 119.

On the other hand, in the receiver shown in FIG. 2, a signal is received by the antenna 129, and then the frequency is converted into an intermediate frequency signal by the frequency converter 130. Then, the intermediate frequency signal is distributed by the distributor 301, one of which is provided to the distributor 161 as it is, and the other is the delay element 145.
And is provided to the distributor 162. Distributor 161
Splits the signal into two, and gives one to the frequency converter 163,
The other is provided to frequency conversion section 164. The distributor 16
2 distributes the signal, and supplies one to the frequency converter 165;
The other is provided to frequency conversion section 166. Frequency converter 16
3, 165 respectively convert the frequency of the intermediate frequency signal using the sine component of the local signal 174 and output the I component. The frequency converters 164 and 166 output the local signal 174
Of the intermediate frequency signal using the cos component of
Output the components. These I component and Q component become substantially baseband signals.

Thereafter, the four signals are correlators 167, 1 having a correlation with the PN code generated by the PN generator 132.
68, 169 and 170 to obtain a correlation output. Thereafter, the undelayed I component output from the correlator 167 and the delayed I component output from the correlator 169 are output.
Is multiplied by the multiplier 171, and the undelayed Q component output from the correlator 168 and the delayed Q component output from the correlator 170 are multiplied by the multiplier 172, and the outputs of the multipliers 171 and 172 are output. The addition is performed by the adder 173. The output of the adder 173 is the data demodulation circuit 1
28 demodulates the data.

Next, the flow of the above signal will be described. The data signal generated by the data generator 111 is represented by A
(T), the PN code is P (t), and the modulator 112,
133 is BPSK modulation, and the local signals L ₁ , L ₂ ,
Let L ₃ and L ₄ be cos ω ₁ t, cos ω ₂ t and c, respectively.
osω expressed in ₃ t, _{cosω 4} t, it indicates the amount of delay in tau. Therefore, the signals A, B, C, and D in FIG. 1 are represented by the following equations.

S ₁ (t) = A (t−τ) P (t−τ) cosω ₁ (t−τ) b S ₂ (t) = P (t) cosω ₁ t C S ₃ (t) = S ₁ (t) + S ₂ (t) = A (t−τ) P (t−τ) cosω ₁ (t−τ) + P (t) cosω ₁ (t) D S ₄ (t) = S ₃ (t ) × cos ω ₂ (t) Here, if only the RF term is taken out, the following equation is obtained: = １ ／ ΔA (t−τ) P (t−τ) cos ((ω ₁ + ω ₂ ) t−ω ₁ τ) + P (T) cos ((ω ₁ + ω ₂ ) t)｝ Thus, a sum signal of two waves delayed by τ in time is also obtained in the RF system.

Next, the signals of the receiver will be sequentially described. E S ₅ (t) = S ₄ (t) × cos ω ₃ t (provided that there is no delay between transmission and reception) =＝ ΔA (t−τ) P (t−τ) cos (( ω ₁ + ω ₂ ) t−ω ₁ τ) · cos ω ₃ (t) + P (t) cos ((ω ₁ + ω ₂ ) (t) · cos ω ₃ (t) と Here, if only the intermediate frequency signal is extracted, It is expressed by the following equation.

= １ ／ A (t−τ) P (t−τ) cos ((ω₁+ Ω_Two−ω_Three) T-ω₁ τ + P (t) cos ((ω₁+ Ω_Two−ω_Three) T) f S₆(T) = S_Five(T) G S₇(T) = 1/4 ｛A (t−2τ) P (t−2τ) cos ((ω₁+ Ω _Two −ω_Three) (T−τ) −ω₁τ) + P (t−τ) cos ((ω₁+ Ω_Two−ω_Three) (T-τ))｝ H₈(T) = S₆(T) × cosω_Fourτ Here, extracting only the baseband signal is expressed by the following equation.
Is done.

= １ ／ A (t−τ) P (t−τ) cos ((ω ₁ + ω ₂ −ω ₃ −ω ₄ ) t−ω ₁ τ) + P (t) cos ((ω ₁ + ω ₂₋ ω ₃ −ω ₄ ) t)｝ If ω ₁ + ω ₂ −ω ₃ −ω ₄ = Δω, the baseband signal is expressed by the following equation.

[0030] = 1/8 {A (t -τ) P (t-τ) cos (Δωt-ω 1 τ) + P (t) cos (Δωt)} Similarly, Li, j, Le also by the following formula Desired.

Re S₉(T) = 1/8 ｛-A (t−τ) P (t−τ) sin (Δωt−ω₁ τ) −P (t) sin (Δωt)｝ nu S_Ten(T) = 1/8 ｛A (t−2τ) P (t−2τ) cos (Δωt− (2ω₁+ Ω_Two−ω_Three) Τ) + P (t−τ) cos (Δωt− (ω₁+ Ω_Two−ω ₀ ) Τ)｝ Le S_{1 1}(T) = 1/8 ｛-A (t−2τ) P (t−2τ) sin (Δωt− (2ω₁+ Ω_Two−ω_Three) Τ) + P (t−τ) sin (Δωt− (ω₁+ Ω_Two− Ω_Three) Τ)｝ The signals of the above-mentioned channels are correlators 167, 168, 16
9 and 170.

FIG. 3 is a diagram showing an output waveform of the correlator shown in FIG. Correlators 167, 16 shown in FIG.
The output waveforms of 8, 169 and 170 are shown in FIG.
(A), (b), (c), and (d) are obtained. Of these, any of the delayed signals contains a data component, so the data value is 1 or -1.

Next, the multiplier 171 includes a correlator 167,
In order to multiply the outputs a and c of FIG.
As shown in (e), the multiplier 72 becomes the correlator 16
Since the outputs b and d of 8,170 are multiplied, the output is as shown in FIG. If the data is 1, the output is as shown by a solid line as shown in FIGS. 3A and 3B, and if the data is 0, the output is as shown by a dotted line.

Here, the output of the correlator shown in FIG.
When expressed by (viii), each is expressed by the following equation.
However, the absolute value is shown normalized to 1.

(I) cosΔωt (ii) A (t) cos (Δω (t + τ) −ω ₁ τ) (iii) −sinΔωt (iv) −A (t) sin (Δω (t + τ) −ω ₁ τ) ( v) cos (Δω (t + τ) − (ω ₁ + ω ₂ −ω ₃ ) τ) (vi) A (t) cos (Δω (t + 2τ) − (2ω ₁ + ω ₂ −ω ₃ ) τ) (vii) −sin (Δω (t + τ) − (ω ₁ + ω ₂ −ω ₃ ) τ) (viii) −A (t) sin (Δω (t + 2τ) − (2ω ₁ + ω ₂ −ω ₃ ) τ (ix) is (ii) × Since the output is (v), the following equation is obtained.

[0036] (ix) A (t) cos (Δω (t + τ) -ω 1 τ) × cos (Δωt- (ω 1 + ω 2 -ω 3) τ) Here, when put between ω ₂ -ω ₃ ~0 , (Ω ₁ + ω ₂ −
ω ₃ ) τ to ω ₁ τ.

= A (t) cos ² (Δω (t + τ) −ω ₁ τ) (x) A (t) sin (Δω (t + τ) −ω ₁ τ) × sin (Δω (t + τ) − (ω ₁ + ω) ₂ −ω ₃ ) τ) = A (t) sin ² (Δω (t + τ) −ω ₁ τ) Therefore, the multiplier 17
When the outputs (ix) and (x) of 1,172 are added, the following equation is obtained.

(Ix) + (x) = A (t) cos ² (Δω (t + τ) −ω ₁ τ) + A (t) sin ² (Δω (t + τ) −ω ₁ τ) = A (t) (cos ² (Δω (t + τ) −ω ₁ τ) + sin ² (Δω (t + τ) −ω ₁ τ) = A (t) Therefore, a data component can be obtained as an output.

As described above, the use of the first embodiment of the present invention eliminates the need for a conventional carrier synchronization loop and enables data demodulation without a carrier cycle.
Therefore, data demodulation could not be performed until carrier regeneration at the time of line disconnection or line return due to multipath fluctuation or the like. However, by using this embodiment, the loss time becomes 0, and in a line where disconnection occurs frequently, Also, it is possible to limit the interruption of data to only the disconnection time.

Further, since the output data does not have the uncertainty of the data due to the phase of the carrier as in the related art, stable absolute data can be obtained.

FIGS. 4 (a) to 4 (f) are waveform diagrams showing a state where a multipath exists on a line and the correlation output is spread with a delay. Since each of FIGS. 4A to 4F is almost in a short time, it can be considered that the time delay is the same, so that outputs as shown in FIGS. 4E and 4F can be obtained. . At this time, since all signals generated by the multipath are demodulated, it can be seen that the PDI effect is obtained.

Further, prior to FIGS. 4E and 4F,
Since what kind of waveform is expected to be output from the outputs (i) and (iii) of FIGS. 4A and 4B, the outputs (ix) and (x) according to the expected data are demodulated. The filtering and the time window can be optimized at the time, and the error rate characteristics can be improved.

Further, in this embodiment, as is apparent from FIG. 3, the coincidence of the correlations by the codes, (a) and (c),
It can be seen that both the coincidence of the correlation output timings coincide with each other as shown in (b) and (d), and as a result, an output as shown in FIG. 4 is obtained. That is, if the signs do not match,
Alternatively, if the correlation timings do not match, no output is made. Therefore, if these two parameters are assigned to each user, it is possible to have a larger number of channels than conventional CDMA using only codes as parameters. As a result, what used to be only a user with only 18 kinds of codes with 127 chips conventionally can now have more users.

FIGS. 5 and 6 show a second embodiment of the present invention. In particular, FIG. 5 shows a transmitter and FIG. 6 shows a receiver. The second embodiment is different from the first embodiment in that the delay element 115 operates with a baseband signal. That is, in FIG. 5, the signal generated by the data
Is multiplied by the PN code generated by the PN generator 132. The output signal of the multiplier 131 is delayed by the delay element 115, while the PN code is
Accordingly, the signal is multiplexed with the output of the delay element 115. further,
The multiplexed signal is converted into a local signal 1 by the modulator 112.
13 is modulated. The modulated signal is transmitted to the frequency conversion unit 11
7, the frequency is converted to the RF band, and the power amplifier 11
8 and is transmitted from the antenna 119.

On the other hand, in the receiver, as shown in FIG. 6, a signal is received by antenna 129 and converted to an intermediate frequency signal by frequency conversion section 130. Then, the intermediate frequency signal is divided into two by the divider 301, and the frequency is converted by the frequency converters 163 and 165 using the sin component and the cos component of the local signal 174, respectively.
Each is divided into two by the distributors 161 and 162. One signal distributed by the distributor 161 is directly input to the correlator 167, and the other signal is input to the correlator 168 via the delay element 175,
A correlation output is obtained from 168. One output of the distributor 162 is input to the correlator 169, and the other output is supplied to the correlator 170 via the delay element 176. Then, correlation signals are obtained from the correlators 169 and 170. Hereinafter, the multipliers 171 and 172, the adder 173, and the data demodulation circuit 128 perform the same operation as in FIG.
The data is demodulated.

Next, the flow of the above signal will be described. Assuming that the data signal and the local signal are the same as those in the first embodiment, the signals a to e in FIG.

S ₁ (t) = A (t−τ) P (t−τ) b S ₂ (t) = P (t) C S ₃ (t) = S ₁ (t) + S ₂ (t) = A (t−τ) P (t−τ) + P (t) d S ₄ (t) = S ₃ (t) × cosω ₁ t = A (t−τ) P (t−τ) cosω ₁ t + P ( t) cos ω ₁ t E S ₅ (t) = S ₄ (t) × cos ω ₂ t Here, when only the RF term is extracted, it is expressed by the following equation.

= １ ／ {A (t−τ) P (t−τ) cos (ω ₁ + ω ₂ ) t + P (t) cos (ω ₁ + ω ₂ ) t) The above equation is sent from the transmitter. Signal. Next, signals for the receiver will be sequentially described.

F ₆ (t) = S ₅ (t) × cos ω ₃
t (provided that there is no delay between transmission and reception) Here, if only the intermediate frequency signal is extracted, the following equation is obtained.

= １ ／ {A (t−τ) P (t−τ) cos (ω ₁ + ω ₂ −ω ₃ ) t + P (t) cos (ω ₁ + ω ₂ −ω ₃ ) t} S ₇ ( t) = S ₆ (t) × cos ω ₄ t Here, taking out only the baseband signal is represented by the following equation.

= 1/8 ｛A (t−τ) P (t−τ) cos (ω ₁ + ω ₂ −ω ₃ −ω ₄ ) t + P (t) cos (ω ₁ + ω ₂ −ω ₃ −ω ₄₎ Here, if ω ₁ + ω ₂ −ω ₃ −ω ₄ = Δω, the baseband signal is expressed by the following equation.

= 1/8 ｛A (t−τ) P (t−τ) cosΔωt + P
(T) cosΔωt｝ h S ₈ (t) = S ₆ (t) × sin ω ₄ t = 1/8 ｛−A (t−τ) P (t−τ) sinΔωt−
P (t) sinΔωt｝ S ₉ (t) = 1/8 ｛A (t−τ) P (t−τ) c
osΔωt + P (t) cosΔωt｝ Nu S ₁₀ (t) = 1/8 ｛A (t−2τ) P (t−2)
τ) cos (Δω (t−τ) + P (t−τ) cosΔω
(T−τ)｝ S ₁₁ (t) = 1/8 ｛−A (t−τ) P (t−
τ) sinΔωt) −P (t) sinΔωt｝ S ₁₂ (t) = 1/8 ｛−A (t−2τ) P (t−
2τ) sinΔω (t−τ) −P (t−τ) sinΔω
(T−τ)｝ The signal based on the above equation (1) to (4) is
70, an output similar to that of the first embodiment is obtained.

Here, when the correlator output of FIG. 4 described above is represented by (i) to (viii), the following equations are obtained. However, the absolute value is normalized to 1.

(I) cosΔωt (ii) A (t) cosΔω (t + τ) (iii) cosΔωt (iv) A (t) cosΔω (t + τ) (v) −sinΔωt (vi) −A (t) sinΔω (t + τ) (Vii) −sinΔωt (viii) −A (t) sinΔω (t + τ) Here, in the multiplier 171 of FIG. 6, the above (ii) ×
(Iii) is the main component, and (vi) × (vii) is the main component at the output of the multiplier 172.

(Ii) × (iii) = A (t) cosΔω (t + τ) × cosΔωt Here, when τ is small, cosΔω (t + τ) to co
Since sΔωt can be set, = A (t) cos ² Δωt (vi) × (vii) = − A (t) sinΔω (t + τ) × (−sinΔωt) = A (t) sin ² Δωt The output of 173 is (ii) × (iii) +
Since (vi) × (vii), it is expressed by the following equation.

= A (t) {sin ² Δωt + cos ² Δωt} = A (t) Therefore, a data component can be obtained as an output from the data demodulation circuit 128.

As described above, also in the second embodiment, data demodulation can be performed in the same manner as in the first embodiment, and the same effect as in the first embodiment can be obtained.

FIG. 7 is a diagram showing a third embodiment of the present invention. 2. Description of the Related Art Conventionally, wireless systems are often used by networking. In that case, as shown in FIG. 7, the service area is cellized, and several terminal stations are installed for each cell. That is, the base stations 201 to 207 are arranged for each cell, and the terminal station 208 is arranged in the cell where the base station 201 is arranged.
To 213 are installed. Similarly, other cells are considered to have terminal stations.

In this case, near the cell boundary line, the required electric field intensity of the base station 201 and the adjacent base station 202 become substantially equal, causing interference. Therefore, in the conventional SS, it is necessary to use different codes in adjacent cells. If there are six adjacent cells and six terminals are provided, (6 + 1)
A code of × 6 = 42 is required, which makes implementation difficult.

However, in the embodiment of the present invention, the cells are separated by using different codes for each cell, and 1
In a cell, a terminal station can be distinguished using a difference in the amount of delay. In this case, seven types of codes may be prepared, and codes can be prepared easily even with 127 chips or the like.

Further, since the delay can be distinguished within the cell, the management within the cell can be performed without being aware of the adjacent cells. Therefore, the number of terminal stations can be freely increased or decreased, and network management becomes easy. Conversely, the delay amount is changed for each cell, and 1
Within one cell, it is also possible to distinguish using a code. As described above, by using this embodiment, a networked wireless communication system can be easily constructed, and a system with a high degree of freedom can be realized.

FIGS. 8 and 9 show a fourth embodiment of the present invention.
FIG. 8 is a block diagram showing, in particular, FIG.
9 indicates a receiver. This fourth embodiment is different from the first embodiment.
In all, it is intended to increase the amount of information transmitted.
You. That is, in FIG.
The generated data is converted to a serial / parallel (S / P) converter 1
81 converts it to a 3-bit parallel signal, for example
Is done. Each of the converted parallel signals is supplied to a multiplier 1
PN generator 185 by 82, 183 and 184
After being multiplied by the same PN code,
87 and 188 change the carrier 189 into PSK.
Different delay times (τ₁, Τ_Two, Τ _ThreeLate with
The multiplexer 19 is connected via the extension elements 191, 192 and 193.
4 given. On the other hand, the PN code is directly used as the modulator 19.
0, the carrier 189 is PSK-modulated,
194 makes the delay elements 191, 192 and 193
Combined with output. The output of the multiplexer 190 is
The frequency conversion unit 117 converts the frequency into an RF signal,
After the power is amplified by the power amplifier 118, the antenna 119
Sent out.

On the other hand, in the receiver shown in FIG. 9, a signal is received by an antenna 129, converted into an intermediate frequency signal by a frequency conversion unit 130, and then divided by a splitter 221.
Divided by four. One distributed output is directly supplied to the distributor 225, and the remaining three distributed outputs have delays (τ ₁ , τ ₂ , τ ₃ ) similar to the delay elements 191, 192 and 193 on the transmission side. Element 222,
223 and 224 and provided to distributors 226, 227 and 228, respectively. Distributor 22
5, 226, 227 and 228 use the sine component and the cos component of the local signal 229 to generate frequency distributions 230, 231, 232, 23
3, 234, 235, 236, and 237, and the correlators 238, 239, 240, 24
1, 242, 243, 244 and 245. The outputs of the correlators 238 to 245 are multiplied by the multipliers 246 to 251 for the I component and the Q component, respectively, without delay and those delayed by τ ₁ , τ ₂ , τ ₃ . The signals are added at 252 to 254, demodulated by data demodulation circuits 225 and 256, converted into a serial signal by a parallel / serial (P / S) converter 258, and become data.

FIG. 10 is a diagram showing only the I component of the output waveform of the correlator of FIG. FIGS. 10A to 10D
, The multiplier 246 multiplies the output of the correlators 238 and 240, the multiplier 248 multiplies the output of the correlator 238 and the output of the correlator 242, and the multiplier 250 outputs the output of the correlator 238 and the output of the correlator 244. And multiply by As a result, the multiplier 246
Output only data delayed by τ ₁ , multiplier 248 outputs only data delayed by τ ₂ , and multiplier 258 outputs data delayed by τ ₃ .

Similar data is obtained for the Q component.
By adding and demodulating the data, data is obtained as in the first embodiment. Then, P / S
The converter 258 outputs serial data.

As described above, according to this embodiment, the first
It becomes possible to transmit information three times in the same occupied band as in the embodiment. In addition, since the same circuit can arbitrarily change the number of times by 1 to 3 times due to the difference in line quality, a large amount of data is transmitted when the C / N is good, and when the C / N is deteriorated for some reason, 1 to 1 times. For example, the transmission amount can be flexibly changed using the same transmission band, circuit, and power.

In the fourth embodiment, the number of parallel data is three, but the number is not limited. Further, also in the twenty-third embodiment, similarly to the first embodiment, the effect of PDI can be obtained even when there is a line multipath and the correlation output has a delay spread.

Further, similarly to the first embodiment, the demodulated signal
Correlator output that is output at a faster timing than the signal
, The integrator and the data demodulator circuits 255 to 257 are used.
By controlling the filtering and the time window, the error rate
It is possible to improve the performance. 11 and 12
FIG. 11 is a view showing a fifth embodiment of the present invention.
Shows a transmitter, and FIG. 12 shows a receiver. This example is
In contrast to the second embodiment shown in FIGS.
This is to increase the amount of information transmission. That is, the figure
As shown in FIG.
The serial / parallel conversion is performed by the S / P converter 181.
The data is converted into 3-bit parallel data. These
The parallel data is processed by multipliers 182, 183 and 184.
Multiplied by the PN code generated from the PN generator 185
And then a different delay time τ₁, Τ _Two, Τ_ThreeHaving
A multiplexer 194 via delay elements 191, 192, 193
And modulated by the modulator 112,
After being converted into an RF signal by the conversion unit 117, the power amplification unit 11
8 and is transmitted from the antenna 119.

On the other hand, in the receiver shown in FIG. 12, a signal received by antenna 129 is converted into an intermediate frequency signal by frequency conversion section 130 and distributed by distributor 132, and then converted by frequency conversion sections 163 and 165. It is converted into a pseudo baseband signal of an I component and a Q component. The pseudo baseband signals of the I component and the Q component are divided into splitters 261 and 262.
, And one of them is directly input to the correlators 268 and 273, and the remaining signals are delayed by the delay elements 263, 264, 265 and 266 having the same delay times τ ₁ , τ ₂ and τ ₃ as those on the transmission side. , 267 and 2
After being delayed at 68, the correlators 270 to 272, 27
4 to 276. Each correlator 26 at this time
Outputs of 9 to 272 and 273 to 275 are the same as those in FIG. Outputs of the correlators 269 to 272 are multiplied by multipliers 277 to 279, and outputs of the correlators 273 to 276 are multiplied by multipliers 280 to 282. Further, multipliers 277 to 279 and 280 to
The output of 282 is added by adders 283, 284 and 285 and demodulated by data demodulation circuits 286, 287 and 288, and then converted to serial data by a parallel / serial converter 289 to obtain demodulated data. .

As described above, according to this embodiment, it is possible to transmit information three times in the same occupied band, as in the third embodiment. Further, the transmission amount can be arbitrarily changed to 1 to 3 times depending on the difference in the line quality, so that the flexible transmission amount can be controlled. Further, the number of parallel transmissions may be any number as in the third embodiment. Further, the effect of PDI can be obtained in the same manner as in the above-described embodiment, and it is also possible to use an integrator of the data demodulation circuits 286, 287 and 288 and a means for improving the error rate characteristics such as controlling the filter time window.

[0071]

As described above, according to the present invention, the phase of data can be demodulated without error without performing carrier reproduction. This eliminates the need for a process for carrier regeneration that was conventionally required, and reduces the time required for carrier regeneration after a line disconnection or a reconnection. As a result, the time required for restarting data demodulation for each disconnection becomes shorter, and the time rate of the line can be drastically increased. Further, by transmitting two waves, users can be identified by two kinds of codes and delay times, so that it is possible to have more users than before. In the case where the network is further divided into individual cells, a network with high flexibility can be constructed by properly using the two. In addition, by transmitting three or more waves, it becomes possible to increase the transmission speed while maintaining the transmission bandwidth and chip rate. By changing the transmission frequency arbitrarily, flexible transmission control according to the propagation path becomes possible. Become.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a transmitter according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram of a receiver according to the first embodiment of the present invention.

FIG. 3 is an output waveform diagram of the correlator shown in FIG. 2;

FIG. 4 is a waveform chart of each part of the embodiment shown in FIG. 2;

FIG. 5 is a schematic block diagram of a transmitter according to a second embodiment of the present invention.

FIG. 6 is a schematic block diagram of a receiver according to a second embodiment of the present invention.

FIG. 7 is a diagram for explaining a third embodiment of the present invention.

FIG. 8 is a schematic block diagram of a receiver according to a fourth embodiment of the present invention.

FIG. 9 is a schematic block diagram of a receiver according to a fourth embodiment of the present invention.

FIG. 10 is a waveform chart of each part in FIG. 9;

FIG. 11 is a schematic block diagram of a transmitter according to a fifth embodiment of the present invention.

FIG. 12 is a schematic block diagram of a receiver according to a fifth embodiment of the present invention.

FIG. 13 is a block diagram of a demodulator using a conventional despreading method.

14 is an output waveform diagram of the correlator shown in FIG.

FIG. 15 is an output waveform diagram of a correlator when there are many multipaths.

[Explanation of symbols]

111 Data generator 112, 133, 186 to 188, 190 Modulator 115, 145, 175, 176, 191-193, 2
22 to 224, 263 to 268 Delay element 116, 194 Combiner 117, 163 to 166, 230 to 237 Frequency converter 118 Power amplifier 119, 129 Antenna 128, 255 to 257 Data demodulation circuit 131, 171, 172, 182 to 182 184,246-2
51,277-282 Multiplier 132,185 PN generator 161,162,225-228,301 Distributor 167-170,238-245 Correlator 173,252-254,283-285 Adder 258,289 P / S conversion 181 S / P converter

Claims (16)

(57) [Claims] 1. A spread-spectrum communication system using direct spreading, comprising: on a transmission side, a signal obtained by modulating a carrier with a spreading code and data, and a signal obtained by modulating a carrier with only the same spreading code as the modulated signal. One of the signals is delayed by at least an arbitrary time equal to or longer than one chip of the spreading code, and the two signals of the delayed signal and the other signal are multiplexed and transmitted. The signal on one path is delayed by the same delay amount as that on the transmitting side, and the delayed signal and the signal on the other path are multiplied by the sin component and the cos component of the carrier frequency signal substantially the same as the transmitting side. Then, the signal is frequency-converted to near the baseband, and a correlation signal obtained from a signal generated by multiplying a signal delayed from the four signals by a sin component, a signal not delayed and a si
The product is obtained by multiplying the correlation output obtained from the signal generated by multiplying the n component and multiplying the correlation output obtained from the signal generated by multiplying the delayed signal and the cos component by the signal not delayed and the cos component. A spread spectrum communication system characterized in that data is demodulated by multiplying a correlation output obtained from a signal and adding the two multiplication outputs. 2. On the receiving side, the data demodulation is performed using an integrator and a filter, and the correlation output of the other path is used as a pilot signal to control the integrator and the filter time window of the data demodulator. The spread spectrum communication system according to claim 1, wherein the spread spectrum communication is controlled. 3. The method according to claim 1, wherein the distinction between the users combines both the spreading code and the delay amount.
Spread spectrum communication system. 4. A communication area is divided into a plurality of areas, and a plurality of communication lines are distinguished by making a difference in the delay time within the same area, and the spreading code is made different between different areas. 2. The spread spectrum communication system according to claim 1, wherein 5. A communication area is divided into a plurality of areas, and within the same area, the communication lines are distinguished by making the spreading codes different, and the plurality of communication lines are provided with a difference in the delay time between different areas. 2. The spread spectrum communication system according to claim 1, wherein 6. A spread spectrum communication system using direct spreading, wherein at a transmitting side, one of a signal multiplied by a spreading code and data and a signal of only a spreading code are delayed, and then the two signals are combined. After transmitting a signal obtained by modulating a carrier wave and modulating the carrier wave signal on the receiving side by multiplying a sinusoidal component and a cos component by a carrier frequency signal substantially the same as that of the transmitting side, and performing frequency conversion to near the baseband, each of the signals is subjected to two paths. And delays the signal of each one path by the same delay amount as that of the transmitting side, and inputs the four signals to four correlators correlated with the spreading code.
a correlation output obtained from a signal delayed by multiplying the n component,
Multiply a correlation output obtained from a signal that is not delayed by multiplying a sin component, and multiply a correlation output obtained from a signal delayed by multiplying a cos component by a correlation output obtained from a signal that is not delayed by multiplying a cos component. A spread spectrum communication system characterized by performing data demodulation by adding the two multiplied outputs. 7. The receiving side performs the data demodulation using an integrator and a filter, and controls the integrator and the filter time window of the data demodulator using the correlation output of the other path as a pilot signal. 7. The spread spectrum communication method according to claim 6, wherein: 8. The method according to claim 6, wherein the distinction between the users combines both the spreading code and the delay amount.
Spread spectrum communication system. 9. A communication area is divided into a plurality of areas, and a plurality of communication lines are distinguished in the same area with the delay time difference, and the spreading codes are differentiated between different areas. 7. The spread spectrum communication method according to claim 6, wherein: 10. A communication area is divided into a plurality of areas, and in the same area, the spreading codes are differentiated from each other, and between different areas, a plurality of communication lines are differentiated by giving a difference in the delay time. 7. The spread spectrum communication method according to claim 6, wherein: 11. A spread spectrum communication system using direct spreading, wherein a transmitting side performs serial-parallel conversion on transmission data to form a data sequence of several bits, and modulates a carrier with each data and a spreading code. Signal and
A signal in which a carrier is modulated with only the same spreading code as the modulated signal is generated, and several types of signals modulated by using data are mutually delayed by an arbitrary time of one chip or more, and there is no other delay from the signal. A signal is multiplexed with the signal on the receiving side, and the receiving side distributes the received signal to the same number of paths as the transmitting side, and delays the signals on the paths except for one of the paths by the same delay amount as the transmitting side. Of the same type of carrier signal as that of the transmitting side
The n component and the cos component were each multiplied and frequency-converted to near the baseband, and all the signals were input to a correlator having correlation with the spread code, and a signal not delayed was multiplied by a sin component. The correlation output obtained from the signals and sin for each delayed signal
The respective correlation outputs obtained from the signals generated by multiplying the components are multiplied, and the correlation output obtained from the signal generated by multiplying the non-delayed signal and the cos component, and the cos component is obtained from the respective delayed signals. Are multiplied by the respective correlation outputs obtained from the signal generated by multiplying the data, the respective data are demodulated by adding the respective multiplication outputs, parallel data is output, and the data is demodulated by parallel-serial conversion. A spread spectrum communication system characterized by the above-mentioned. 12. On the receiving side, the data demodulation is performed using an integrator and a filter, and a correlation output output on a path without delay or a correlation output output at a timing earlier than the demodulation is used as a pilot signal. The spread spectrum communication system according to claim 11, wherein the integrator and a filter time window of the data demodulator are controlled. 13. The spread spectrum communication system according to claim 11, wherein a transmission rate is made variable by changing the number of signals to be multiplexed. 14. A spread spectrum communication system using direct spreading, wherein a transmission side performs serial-parallel conversion on transmission data to form a data sequence of several bits, and multiplies each data by a spreading code. Is delayed from the signal of only the spreading code by an arbitrary time of one chip or more, and thereafter, a signal obtained by multiplexing all the signals and modulating the carrier is transmitted. After multiplying the sine component and the cos component of the substantially same carrier frequency signal, respectively, and frequency-converting the signal to near the baseband, the signals are distributed to the same number of paths as the transmitting side, and the signals of the paths except one of the above are divided into the aforementioned signals. Each signal is delayed by the same delay amount as that on the transmitting side, and all the signals are input to a correlator correlated with the spreading code, and the signal is delayed by multiplying by a sin component. The correlation output obtained from the signal obtained by multiplying the correlation output obtained from the signal and the respective correlation output obtained from the signal delayed by multiplying the sin component, and the correlation output obtained from the signal not delayed by multiplication by the cos component, , Multiplying each of the correlation outputs obtained from the signals delayed by multiplying by 1, multiplying the respective multiplication outputs, demodulating the parallel data, and performing the parallel-serial conversion to demodulate the data. , Spread spectrum communication system. 15. On the receiving side, the data demodulation is performed using an integrator and a filter, and a correlation output output through the non-delayed path or a correlation output output at a timing earlier than the demodulation is used as a pilot signal. 15. The spread spectrum communication system according to claim 14, wherein the integrator and the filter time window of the data demodulator are controlled. 16. The transmission rate is varied by changing the number of signals to be multiplexed.
4 or 15 spread spectrum communication systems.